Steam heating system



July i8 1950 o. A. HUNT ETAL STEAM HEATING SYSTEM 3 Sheets-Sheet l FiledFeb. 26, 1949 /r/ .//Lfe f 1122575 July 18, 1950 o. A. HUNT ErAL STEAMHEATING SYSTEM Filed Feb. ze?, 1949 3 Sheets-Sheet 2 Muir-. Nl@

man wenn Patented July 18,l 1950 UNITED STATES PATENT `OFFICE STEAMHEATING SYSTEM Orville A. Hunt and Louin Tiller, Chicago, 1li.,

assignors, by mesne assignments, to Reconstruction Finance Corporation,Chicago, lll., a corporation of the United States Application February26, 1949, Serial No. 78,604

subject matter related hereto are: S. N. 78,605,

filed February 26, 1949; S. N. 78,842, filed February 28, 1949; S. N.78,843, iiled February 28, 1949; S. N. 80,802, illed February 28, 1949;and S. N. 777,894, iiled October 4, 1947.

The general object of our invention is to achieve greater efliciency ina steam system by heat conservation and better heat transfer andpreferably to do so by means oi a compact automatic master control thatmay be manufactured as a self-contained packaged unit for incorporationin existing steam systems.

A feature of the above mentioned patented system is operation in apulsating manner4 to provide pressure pulsations in the steam chests oi'the system and velocity surges in the return lines. Such pulsatingoperation is advantageous in many respects and is of special importancein reducing resistance to heat flow on the part of condensate iilms andfilms of non-condensible gas that are inevitably formed on the inside ofthe steam chests of heating equipment. One of the specific objects ofthe present invention is to provide improved pulsating action, animproved pattern of pulsation and positive control over the duration andfrequency of the pulsations.

Other objects `of the invention relate to the problems of control andeconomy. in the operation of a steam system of the type set forth in theabove mentioned patent. Such a steam system is characterized by therelease of fluid from the return end oi.' the system into a region ofsubstantially lower pressure for `the maintenance and regulation of flowvelocity in the system. 'I'he steam system is what may be termed a clearchannel system with open communication from the en'd of the return lineback through the steam using equipment to the steam source (no traps) sothat the velocity throughout the system will be responsive to thepressure' drop at the end oi' the return line created by the release oi'fluid. In this method of operation a 2 small fraction of the total steamsurvives to the end of the return line and is termed "acceleration steambecause its release accelerates velocity throughout the system.

Two problems arise in this method of operating a steam system: rst, tocontrol the release of acceleration steam eiectively, and second, tomake the release of steam as economical as possible. The accelerationsteam must be released in such amount and such manner as to maintain aparticular velocity level or range of velocity best suited for ltheparticular steam system and for maximum economy the B. t. u.s of.

the released steam must be reclaimed.

In the disclosure o1 the above mentioned Harrison patent these twoproblems of control and economy are met by using a. thermostatic valveto govern the release of acceleration steam and using make-up water tocool the thermostat elementfof the valve. Control by the make-up wateris highly satisfactory because a specic minimum make-up water demand isinherent in every steam system and may therefore serve as a reliablebase for velocity regulation. And it is economical to use make-up waterto cool the thermostat because the steam released by the thermostaticvalve preheats the make-up water. The make-up water carries thereclaimed heat units directly to the boiler to keep them in the steamsystem.

It is possible to control ,the ow velocity of a steam system in this wayby the inherent demand for make-up water by the system, no matter howsmall that demand may be. It is easier to establish this kind ofcontrol, however, when the make-up water demand of the steam system isof substantial quantity. In a laundry, for example, the make-up Waterdemand is relatively high, say, on the order of 50% of the total boilerfeed- `water when the wash water for laundry operation is heated byintroducing steam and condensate from the system directly into the washwater in an open tank.

When no steam or condensate in any substantial quantity is taken fromthe system the makeup water demand may be relatively small. In alaundry, for example. if the wash water is heated by steam coils and thecondensate from the steam coils is returned to the boiler the make-upwater demand will be small in quantity. In such a situation care istaken to set up a triggering action whereby a small increment of waterreaching a thermostat causes the release of a suitably larger quantityof steam. Such triggering action 6I makes it possible to set up andregulate high 3 I A velocity flow through a steam system by means of andon the basis of a relatively small demand for make-up water.

As for economy in reclaiming the heat units of the released steam bymake-up water there is va limiting factor in the number of B. t. u.sthat can be transferred to a given quantity of water.

'I'his limiting factor becomes important when the make-up water demandis small while the required amount of acceleration steam to be releasedis relatively large.

Itis apparent then that while the use of makeup water to cool thethermostat element of a thermostatic valve is practical. no matter howsmall the make-up water demand of a steam system, nevertheless it wouldbe advantageous in certain situations to have available other means ofcontrolling the release of acceleration steam and reclaiming the B. t.u.s of the released steam.

A purpose of the present invention is to provide other means than thecooling action of `make-up water on a thermostat element to achievereliable velocity control combined with economical use of the releasedsteam. The object is to supplement or replace entirely the cooling eiectof the make-up water for creating system-wide velocity.

In various practices of the present invention this object may beattained by recycling makeup water, by recycling condensate, byrecycling a mixture of make-up Water and condensate, and by withdrawingcondensate from some point in the system to supplement or replace themakeup water. Other means to the same end apart from cooling action onthe thermostat element of the thermostatic valve may be action carriedout upstream from the thermostatic valve. One such action may be thecontinual Withdrawal or pumping of condensate from the return line forthe creation of velocity in the system. Another such action may be thecondensing acceleration steam upstream from the valve for the creationof flow velocity in the system.

Further objects of the invention relate to flexibility or adaptabilityin a control unit of the character described. Flexibility is especiallyimportant because the unit must be adapted to the specific requirementsof widely diiferent steam systems. In this regard another object of theinvention is to provide an exceptionally extensive range ofadjustability permitting the control unit to be tuned or adjustedprecisely to the particular requirements 'of widely different steamsystems.

A further object of the invention is to provide means for promoting owvelocity in the steam system by fluid released from the return side ofthe system without incurring the 'ilash losses that characterize aconventional open steam system. In this regard it is proposed, ineffect, to combine the advantages of open and closed steam systems. theadvantage of an open steam system being the availability of a ,largepressure diierential for creating flow velocity and the advantage of aclosed steam system being the maintenance of condensate under pressureto prevent ash losses.

A further object of the preferred practice of the invention is not onlyto promote velocity in the system by pressure drop at the end of thereturn line, but also to deliver the make-up water to the boiler at ahigher temperature than possible in any conventional steam system. Thisdual object is accomplished by transferring heat from the return line tothe make-up water as the make-up water travels from the usual feed pumpto the boiler. Thus the make-up water causes condensation in the returnline to promote ilow velocity in the system and at the same time is'itself raised to a high temperature on the order of 300 F. It ispossible to heat the make-up water to this high temperature and to do sowithout creating any pumping problem because the additional heatingoccurs on the discharge side of the feed pump where the water is underhigh pressure.

The above and other objects and advantages of the invention will beapparent in the following description taken with the accompanyingdrawings.

In the drawings. which are to be considered as merely illustrative: g

Fig. 1 is a front elevation of a typical embodiment of the invention asa self-contained master control unit;

Fig. 2 is a diagram of a representative steam system incorporating oneform of the new control unit; and

Fig. 3 is a similar diagram illustrating other practices of theinvention.

Fig. 1 illustrates how the invention may be embodied in a piece ofapparatus that may be manufactured as a self-contained unit forinstallation in steam plants, usually in the boiler room. This form lofthe unit includes an upright tank or receiver III and a housing orcasing II associated therewith. The housing may completely enclose thetank or may, as in the present construction, extend forward from thetank to provide an enclosed space for the numerous elements that make upthe control combination. The casing may be sheet metal construction withupper and lower sliding doors I2 that may be opened for access to theinterior. The casing includes a panelboard I3 onwhich are variousindicating devices that will be described later.

Fig. 1 shows six pipes'connected to the master control unit. These sixpipes are: a pipe I4 for supplying supplemental cooling water to theunit; a pipe I5 for supplying new Water to the unit; a pipe I6 connectedto the discharge side of the usual boiler feed pump; a pipe Il which isthe boiler feed line for supplying water to the boiler; the return lineI8 oi the steam system and, at a lower level, the pipe 20 to the intakeside of the boiler feed pump. If desired, an additional vent pipe 2| maybe connected to the vent opening of the tank I0.

Fig. 2 shows diagrammatically the principal elements of a steam systemincluding the important lparts of the new master control unit. The partsof the unit itself are shown inside a rectangle 22 indicated .by abroken line in Fig. 2. Everything inside this rectangle in Fig. 2 isinside the casing II of the unit shown in Fig. l.

In the system shown in Fig. 2, steam from a boiler 23 is suppliedthrough a header 25 to a plurality of equipment heat exchangers or steamusing devices 26. Such devices may be, for example, the various machinesin a laundry or the drying equipment used in paper manufacture.plastics, etc. Return pipes 2l from the various pieces of equipmentconnect with the previously mentioned return line I8.

Instead of traps, each of the return lines 21 is provided with asuitable restriction such as a nipple 28 of relatively small diameter.It will be noted that in such an arrangement there will be opencommunication from the return line I8 back through the various pieces ofequipment.

The condensate that is separated from the steam gravitates through apipe 33 to the intake side of a condensate pump 35 that is included inthe working parts of the master control unit.

`The pump 35 discharges the condensate upward through a pipe 36.Preferably the pump 35 operates continuously.

A valve 31 is provided in the pipe 33 to cut the heat exchanger off fromthe pump 'if desired. When the valve 31 is closed all of the condensateand steam that reaches the heat exchanger 3| must flow from the heatexchanger through a pipe 38. The pipe 3B conducts uid from the returnline I8 into the receiver tank l0.

The pipe 38 leads to 'a two-stage combined heater and mixer 40 which inturn communicates with a spray head 4|. Flow through the pipe 3B intothe tank l0 is controlled by a thermostatic valve 42 having a thermostatbulb 43 extending into the spray head 4I. The thermostat control is suchthat the valve 42 opens in response to decrease in temperature of thethermostat bulb 43 and closes in response to increasing temperature ofthe bulb. The critical temperature at which the valve opens and closesmay be varied by virtue of a manual adjustment 45 on the thermostaticvalve 42.

The steam or steam mixed with condensate that flows through the pipe 38and the valve 42 enters a central upright passage 46 in the twostageheater 40 and divides, one .portion iiowing into an upper jet 41 for thefirst stage heating of new water, and the other portion iiowing into alower jet 48 for the second stage heating. The upper jet 41 is directedinto a Venturi throat 56 and the lowerjet 48 is directed into acorresponding Venturi throat 5|, each jet and throat forming a lowpressure space for the introduction of fluid. 1

New water for the steam system from the previously mentioned supply pipel5 passes through a float-controlled valve 52 and through a ventcondenser 53 to a pipe 55 that enters the twostage heater 46 in the lowpressure space between the rst jet 41 and Venturi throat 50. Theresulting mixture flows through a lateral connecting .passage 56 intothe low pressure space between the second jet 48 and second Venturithroat 5|, where it is joined by the second portion of hot iiuid fromthe pipe 38. From the twostage heater the heated water flows into thespray head 4I in heat exchange relation with the thermostat bulb 43. Thewater is not only heated but is also under considerable pressure in thespray head 4| and is discharged downwardly through the spray ports withconsiderable violence.

Preferably the tank l0 is maintained slightly above atmosphericpressure, say, 3 or 4 lbs. above atmospheric pressure. For this purposethe tank is of closed construction and the vent 2| is provided with botha vent valve 58 and a relief valve 59. The vent valve 58 may be adjustedat a slightly open position to maintain the desired `the spray header 4|will be so limited relative to the input of fluid that the pressure inthe spray header will rise above the pressure prevailing in the tank ||lwhenthe thermostatic kvalve 42 is open. Under such conditions thepressure in the spray header may go substantially above the tankpressure. It is further contemplated that the extent to which .pressurewill rise in the spray header under given conditions may be variedeither by varying the number of spray openings or changing the size ofthe spray openings.

When the heated water is released in finely divided particles from thespray header 4| into the interior of the tank i6. the water particlesare shattered by flashing action and the noncondensible gases areeiectively released from the water to escape upwardly through the ventopening 2|. The vent condenser 53 not only reclaims heat from theescaping gases but also condenses any vapors that tend to escape withthe gases, the recovered condensate dripping to the bottom of the tank.

The tank I0 contains in its lower portion a reserve body 60 of thedeaerated make-up water supplied by the above described spray action.When the level of this body drops, a suitable iioat 6| opens thepreviously mentioned valve 52 by suitable mechanical means including anupwardly extending operating rod 62. If the level of the water body 60rises too high, it overflows through an overflow pipe 63. To prevent therelease of pressure through the overflow pipe 63 the overiiow pipeis'provided with a float valve 64 that is normally closed but opensautomatically whenever the waterlevel in the tank rises unduly. Whendesired, the whole water content of the tank may be iiushed out byopening a draink valve 66.

In the preferred practice of our invention the master control unit isprovided with means for introducing and controlling pulsations in thesteam system. An example of such an expedient is the use of anintermittently operated water valve 10 shown in Fig. 2.

The water valve 10. which is in series with the previously describediioat valve 52 to control the water ow into the vent condenser 53, is ofthe solenoid type controlled by an electric circuit, the valve beingopen when the circuit is energized and being closed when the circuit isdeenergized.

A pair of wires 1| supply current to a timer 12 and wires 13, 14 and 15complete the circuit with the solenoid valve 10 in series with a mercuryswitch 16. The mercury switch 16 is on a rocker arm 11 of the iioatcontrol mechanism actuated by the float 6| and closes whenever the floatdrops in response to demand for new make-up water;

Thus, the valve 10 is intermittently operated during any period inwhichthe float control valve 52 is open. It is apparent that the i'loatcontrol valve 52 may be omitted entirely if desired. The timer 12 is ofa well known type that is'manually adjustable to divide a fifteen-secondtime period into two parts in any desired proportion. For example, thetimer may, in repeated cycles, cause the solenoid of the valve 10 to beenergized for five seconds and de-energized for ten seconds.

The deaerated make-up water, usually at above 212 F. by virtue of thepressure existing in the tank I0, is taken from the tank through thepreviously mentioned pipe 20 to the intake side of the usual boiler feedpump 61 and is discharged by the pump into the previously mentioned pipeI6 that is connected to the control unit at'the top. 'I'he pipe I6 isconnected to the inlet end of a heat exchange coil 68 in the previouslymentioned combined heat exchanger and steam separator'3l. The outlet endof this coil 68 is joined to the previously mentioned pipe 36 from thecondensate pump 35 to supply the previously mentioned boiler feed lineas indicated in Fig. 2.

Inside the master control unit means may be provided to divert at leastsome of the discharge from the boiler feed pump 61 directly into theshell of the combined heat exchanger and separator 3|. For this purposethe pipe in the master control unit that connects with the pipe I6 fromthe boiler feed pump 6l is provided with a branch |03 leading to a sprayhead |04 inside the separator 3| and two manually adjustable valves |05and |08 are provided as shown to permit variation in proportioning theflow between the coil 68 and the spray head |04.

The feed water pump 61 may be controlled in a well-known manner by meansresponsive to changes in the water level in the boiler 23 or in somepractices of the invention may be manually adjusted to run continuouslyat approximately the rate required to keep the boiler level constant. Ineither event, the oat 6| in the master control tank |0 will dropperiodically to cause new water to be supplied to the system in accordwith the boiler demand. Since the boiler demand for make-up water varieswith the heatload on the system, it is apparent that the master controlunit is responsive to changes in the heat load on the system.

A second expedient .that may be used to create and control pulsations inthe system instead of the solenoid valve 10 or in addition to thesolenoid valve is the use of intermittently flowing water from anysuitable source entirely independent of the water demand by the boiler.

In the particular arrangement shown in Fig. 2, s. small circulatingpump, has its intake |3| connected to the tank |0 to draw watertherefrom. 'I'he output from the pump is delivered through a, pipe |32to the previously mentioned pipe 55 so that it may reach the thermostat43 to cause opening action of the thermostatic valve 42. A check valve|33 prevents back flow. Preferably, a by-pass |34 having a by-pass valve|35 y valve |36 in the pipe |32 may be manipulated to vary the amount ofrecirculated fluidy that reaches the pipe 55.

. In some instances it is desirable to cool the discharge from thecirculating pump |30 for greater cooling effect on the thermostat 43.For this purpose, Fig. 2 shows the discharge from the circulating pump|30 as passing through the coil |31 of a heat exchanger |38. The heatexchanger |38 is provided with an intake pipe |39 and an outflow pipe|40 so that any suitable fluid medium may be circulated therethrough.

Preferably, the circulating pump |30 is operated intermittently to causepulsating ow through the pipe |32 and preferably the pulsations of thisflow are synchronized with the pulsations of ilow through the pipe whenthe unit -along with non-condensible gases.

a cable |4| that is connected in parallel with the solenoid valve 10 tobe operated simultaneously therewith by the timer 13.

Operation The manner in which the steam system operates and iscontrolled by the described unit may be understood from the foregoingdescription.

Steam condenses in each one of the steam chests in the pieces ofequipment 26 to give up heat to the material in process, but a portionof the steam flows continuously into the return line |8 through therestrictions 28 because of the open communication through the system. Inthis method of operation, the flow velocity is substantially higher thanthe overall or average velocity in a conventional trap system and thesmall proportion of steam that is continuously passing through therestrictions 28 effectively carries the condensate out of the steamchests The drop in pressure at the restrictions 28 causes some of thecondensate to flash into steam thereby slightly increasing the steamcontent of the fluid mixture that reaches the combined heat exchangerand separator 3|.

The adjustment 45 of the thermostatic valve 42 is high enough to makethe valve open in an intermittent manner thereby to cause pulsating flowthroughout the system. In a steam system having approximately lbs. persquare inch gauge Ypressure in the steam header 25 the setting of thethermostatic valve may be, for example, somewhat above 230 F. In anyevent the temperature setting of the thermostatic valve will be abovethe normal temperature prevailing inside the tank I0. If the tank I0 isat 4 to 6 Ibsgauge lpressure the temperature therein will be-in therange 224-230 F.

Since the temperature in the master control tank is below thetemperature setting of the thermostatic valve the environment of thespray header 4| tends to cool the thermostat bulb below the temperaturesetting thereby to cause the thermostatic valve 42 to open. When thevalve 42 opens, however, the thermostat bulb is again heated above itscritical temperature by the fluid released from the separator 3| therebycausing the thermostatic valve to close.

Since a temperature above 230 F. cannot be attained in the spray head 4|aslong as the spray head interior is at the same pressure as theinterior of the tank l0 the initial flow of steam from the thermostaticvalve'or the initial flash of steam by flash action from condensatereleased through the valve does not have a temperature above 230 F.Since the restrictive action of the spray openings is effective to causerisingv back pressure in the spray header, however, the temperaturerises correspondingly and soon climbs above the temperature setting ofthe thermostatic valve. It is apparent then that the flow passage fromthe thermostatic valve 42 to the discharge openings of the spray header4| functions as a pressure accumulation space to make possible therelatively high temperature required for the purpose of valve control aswell as for the purpose of deaerating the make-up water.

By virtue of the described cycle of alternate heating and cooling, thevalve 42 opens inter-. mittently in an automatic manner to maintain adesired minimum average'ow velocity in the system during periods when nonew make-up water is flowing. Whenever new make-up water is required thefloat Il lowers to open the water valve 52 and at the same time themercury switch l tilts to close a circuit through the solenoid valve l0and timer 12. As long as the iloat 6l is lowered the solenoid valve 'Inopens intermittently to release pulses of make-up water for ilow throughthe vent condenser 53 and pipe 5S into the two-stage heater-mixer 40.Each pulse of water causes the thermostat 43 to be cooled thereby toopen the thermostatic valve 42 for the release of steam from the system.The steam mixes with the new water and the new water released by thespray header 4l under pressure and at a temperature higher than 212 F.is eil'ectively deaerated. The deaerated water drops to the bottom ofthe tank III while the released non-condensible gases ilow upward to thevent 2|. The vent condenser 53 not only condenses any vapors that maytend to escape butvalso reclaims heat from the separated gases.

In the usual method of operation the ilow of new water is adequate tokeep the thermostatic valve 4`2 open in opposition to the heating ef'fect released by the thermostaic valve, so that the thermostatlc valvestays open as long as the ilow of new water continues. As soon aswaterilows into the two-stage heater-mixer ceases, the thermostaticvalve immediately closes in response to the high temperature iluld fromthe return line. Thus the thermostatic valve will open and close inresponse to each pulse of water released by the solenoid valve 1B.

This continual interruption of the water flow by the solenoid valve hasimportant effects. It increases the amplitude and abruptness of thepulsations throughout the steam system. It increases the frequency ofthe pulsations by increasing the frequency of the water cooling effectson the thermostatic bulb 43. It also stretches out the periods of timein which the demand for new water by the boiler is effective to createpulsations in the system.

Although opening the thermostatic valve 42 to createvelocity may tend tolower' the pressure of the condensate delivered to the condensate pump35, the valve opens only intermittently so that such tendency to droppressure can occur only intermittently.

A special advantage of this adjustable arrangement for breaking themake-up water ilow into pulses is that the rate at which new water issupplied and deaerated may be more or less independent of the action ofthe boiler feed pump 61. For example, the boiler feed pump 61 may, in agiven installation, operate for five minutes and then remain idle fortwenty minutes. During the ve minutes of pump operation the water levelofthe reserve body of make-up water 60 in the tank Ill will drop severalinches. During the following twenty minutes in which the pump is *idlethe solenoid valve 10 will release pulses of water into the receiver torestore the water level.

The timer 12 may, if desired, be so adjusted that the time taken for thewater level to be restored is approximately twenty minutes. Thus the newwater is sent through the deaeration process gradually, notwithstandingthe periodic abrupt drops in the water level inside the tank I0.

The valve 42 may compeltely close or only nearly close in response torising temperature,

and the valve may be either a quick-acting valve or a slow-acting valve.If a slow-acting valve is used, it will tend to stay Open at anequilibrium in doing so speeds up velocity at the return end of thesystem, the unit may be said to tie the two ends of the system togetherfunctionally. The result is a closed chain of causes in which thedemandv of the boiler for a pound of water to replace a, pound of steamconsumed in the system' vcauses enough velocity to be created to sweepout the resulting condensate from the steam chests in the system. v

When the load on the steam system is steady the master control unitfunctions as automatic means to keep the overall or average velocity otthe pulsating flow at a substantially constant level. Under constantoperating conditions, with the average velocity level of the pulsatingflow substantially constant, the boiler demand for new water will be metby a substantially constant ratio of new water to condensate. Under suchcircumstances if velocity were to tend to lag, there would be animmediate decit to condensate returned and the demand for make-up waterwould temporarily increase. Such increase in the demand for make-upwater would, however. act on the thermostat bulb 42 to increasevelocity.l Thus. any tendency for velocity to drop would beautomatically corrected. In like manner any tendency for velocity tospeed up excessively, would be automatically corrected by reducing thedemand for make-up water and thereby reducing the quantity of uidreleased by the valve 42.

Such changes in the load on the steam system cause corresponding changesin the demand for Anew water by the boiler with corresponding changes inthe quantity of make-up water required in a. unit of time. it isapparent that the average or overall velocity of the system also shiftsup and down automatically with changes in the load on the system.

Each ,time the valve 42 opens. it causes two things to happen. It causesa pressure pulsation or slight pressure drop in every steam chest in thesystem,and it causes velocity in the whole system to speed up. In otherwords, each opening movement of the valve 42 causes a pressure pulsationin each piece of equipment and at the same time causes a strong surge offlow from the equipment through the return line of the system. Thepressure pulsations attack the non-condensible gas films in thesteamchests by causing a ilashing action because each timev the pressuredrops slightly, a portion of every particle of water in the steam chestsashes into steam.V

There are countless water particles in and near the gas iilm and at lbspressure per square inch the condensate that ilashes into steamincreases in volume over 240 times. As a result, each particle of waterbecomesan explosive center of turbulence to disrupt the gas films and topromote heat transfer to the material in4 process. 'I'he gases torn awayfrom the gas fllms are quickly picked up by the velocity surges andswept into and through the returnl line of the system. The velocitysurges also sweep condensate out of the steam chests continuously andkeep the condensate films exceedingly thin.

Only high temperature water reaches the boiler 23 because the condensatethat isreturned directly to the boiler through the pump 35 is notpermitted to drop to atmospheric pressure and because all new wateradded to the system is eil'ectively preheated. In a system using steamVat 100 lbs. per square inch, the condensate-passed through the pump 35is maintained well above The new water is heated in four stages and thenis intermixed with the high temperature con- 'densate in the boiler feedline I1. The first stage of heating the new water is in the ventcondenser 53; the next two stages are in the two-.stage heater 40; andthe fourth stage is accomplished by the coils 68 in the combined heatexchanger and separator 3l.v As a result, the temperature of the make-upwater as it leaves the coils 68 is nearly 300.

It is apparent that the arrangement shown in Fig. 2 supplements thevelocity-creating effect of the make-up water in several ways. In thenrst place, the relatively cool water or condensate supplied through thepipe I4 supplements the cooling effect of the make-up water on thethermostat 43. In the second place, because the tank I is underpressurethe cooling effect of the vent condenser 53 reduces theVpressure and temperature inside the tank with consequent cooling actionon the thermostat 43. In the third place, the continuous removal ofcondensate by the pump 35 from the lower end of the separator 3| createsow in the return line I8. In the fourth place, the condensing of steamin the separator 3| by the cooling effect of the water coil |58V and/orthe cooling effect of water introduced by the spray head |04 serve topromote flow by contraction of the fluid mixture at the end of thereturn line.

All of these factors working together create and maintain whatever flowvelocity. is desired in any particular steam system independently of themake-up water demand of the system and regardless of how small themake-up water demand may be. This arrangement, moreover, causes all heatunits of the acceleration steam to be reclaimed and make it unnecessaryfor acceleration steam to be wasted. j

In variouspractices of the invention with the described apparatus,various parts may be taken ont of operation if desired. Thus, as alreadynoted, the condensate pump 35 may be cut oiI so that all the iluid fromthe return line I8 passes through the thermostatic valve 42 into thetank I0. To change over to this mode of operation it is necessary merely.to close the valve 31 to cut off the condensate pump 35 and to raisethe temperature settings of the thermostatic valve 42. When the mastercontrol unit is operated in this manner it does not return condensatedirect- 1y to the boiler under pressure but it does recirculate all ofthe condensate through the deaeration process to eliminate any air thatmay be picked up by the condensate.

It is obvious also that the circulatingl pump |30 may be kept out ofoperation in those instances in\which the cooling effect of the makeupwater alone on the thermostat 43 is sumcient to keep the systemoperating at high eiciency.

The instrument panel In the preferred form of the invention the panelboard I3 is provided with the following 1nstrumentalities. A dial 81indicates the deaera- .tion temperature and a dial 83 indicates thedeaeration pressure, both values being taken near .the thermostat bulb43 where the lfluid under pressure flows into the spray head 4|. A dial88 shows the return line pressure near the point at which the returnline I8 connects with the combined heat exchanger and separator 3|. Adial 90 shows the temperature of the feedwater delivered to the boilerthroughv the feed line I1 and a dial 9| shows the pressure of themake-up water supply taken near the connection of the water supply pipeI with the unit. A dial 92' indicates the pressure prevailing inside themaster control tank I0. Asignal lamp 95 is-responsive to the mercuryswitch 'I6 to indicate the periods in n which the system is taking innew water, and a second signal lamp 96 responds to energization of thesolenoid valve 10 to indicate the occurrence of water pulses into thetwo-stage heater 40.

Tuning the unit to suit a particular steam system V system Within a verywide range. As a result, the

control unit is extremely flexible and is not only readily adaptable tothe requirements of any particular system but is also adaptable tochanges in a steam system such as the addition of new heating equipment.

Any of the following adjustments may be made to vary the operation andcontrol characteristics of the unit: l

1. The temperature adjustment 45 of the thermostatic valve 42 may bevaried.

2. The rate of supply of the new water may be I varied to change thecooling eiect of the new water on the bulb 43. For example, the floatvalve 52 may be restricted or limited in its opening action to anydegree desired.

3. The closing action of the thermostatic valve 42 as well as theopening action may be limited to any degree desired.

4. 'Ihe discharge capacity of thespray head 4| may be varied to vary themanner and degree oi pressure rise in the spray head.

5. The prevailing pressure in the master control tank |0 may be raisedor lowered.

6. The proportion of make-up water diverted to the spray head |04 in theseparator 3| may be varied by manipulation of the valves |05 and |06.

7. The duration of the water pulses controlled by the solenoid valve 10,as well as the water pulses generated by the circulating pump |30, maybe varied by adjustment of the timer 13.

8. The proportion of the water recirculated past the thermostat 43 bythe pump I 30 may be varied by adjustment of the two valves |34 and |35.

9. The temperature of the water recirculated by the pump |30 may bevaried by varying either the temperature or rate of flow of the coolingmedium employed in the heat exchanger |31.

f Description' of Fig. 3

The arrangement illustrated in Fig. 3 is largely similar to thepreviously described arrangement in Fig. 2 as indicated by the use ofcorresponding numerals to indicate corresponding parts.

One respect in which Fig. 3 differs from Fig.l 2 is in the omission ofthe circulating pump |30,

but it is to be understood that the circulating Y 13 pump may be added,if desired, In any particular installation.

The purpose of Fig. 3 is to illustrate how cooling water from somewherein the steam system apart from the master control unit may be introducedinto'the master control unit to supplement the cooling effect ofthemake-up water on the thermostat 43. For this purpose Fig. 3 shows pipeI4 connected to the pipe 55. The pipe I4 may bringr cooling fluid to theunit from various sources of cooling water in various practices of theinvention. In the present arrangement the cooling water is condensatesupplied by a piece of steam using equipment II2 that operates onlow-pressure steam. Fig. 3 shows a supply pipe II3 from the steam header25 to the piece of equipment II2, this supply pipe being provided with asuitable pressure reducing valve I I5. Thereturn pipe IIB from the pieceof equipment II2 may be provided with a suitable restriction III and isconnected to the coil yIIB of a heat exchanger I I9. The other end ofthecoil IIB is connected to the pipe I4.

The heat exchanger IIS has an inflow pipe |20 and an outflow pipe'IZI topermit any suitable virtue of this arrangement cooling water flowsV tothe master control unit through the pipe I4 to supplement the coolingeiect of the make-up water on the thermostat 43 and the pulses of waterfrom both sources occur more or less simultaneously.

Our description in detail of preferred practices of the invention forthe purposes of disclosure and to illustrate the principles involvedwill suggest to those skilled lin the art various changes andsubstitutions under our basic concepts. We reserve the right to all suchdepartures from our disclosure that fall within the scope of ourappended claims.

We claim as our invention:

3. In a steam system, a combination as set forth in claim l, whichincludes a valve for controlling 1. In a steam system of the characterdescribed having a steam source, at least one steam-using device and areturn line, the combination therewith of means to promote flow velocitythrough the system, said dow-promoting means including: a valve torelease fluid from said return line into a region of substantially lowerpressure, a thermostat for causing opening operation of said valve inresponse to temperature below a given temperature and closing operationof the valve in response to temperature above said given tem-- perature,said thermostat being positioned to oe heated by the fluid discharge ofthe valve, means to flow relatively cool condensate from the system intoheat-exchange relation with said thermostat for opening action of saidvalve, and automatic means to break said flow into short flow periodsfor intermittent operation of the valve to create pulsations in thesteam system.

2. In a steam system, a combination as set forth in claim l, in whichthe iiow of said condensate is controlled by a valve and an automaticlcontrol continually opens and closes said valve to break up the flow ofthe condensate.

the flow of said condensate and an automatic timer controlling theoperation of said condensate valve, said timer operating said condensatevalve periodically and being adjustable with respect to such periodicaction.

4. In a steam system of the character described having a steam source,at least one steam using device and a return line, the combinationtherewith of means to promote flow velocity through the system, saidflow-promoting means including: a valve to release fluid from saidreturn line into a region of substantially lower pressure, a thermostatfor causing opening operation of said valve in response to temperaturebelow'a given temperature and closing operation of the valve in responseto temperature above said given temperature, said thermostat beingpositioned to be heated by the fluid discharge of the valve, a firstmeans effective to provide a stream of make-up .Water `to cool saidthermostat inresponse to demand for\makeup water by the system, and asecond means to automatically reduce the oW of said streamintermittently when said rst means is effective.

5. In a steam system, a combination as set forth in claim l whichincludes a heat exchanger to reduce the temperature of said condensatebefore the condensate reaches said thermostat.

6. In a steam system, at least one steam-using device, a steam sourceconnected therewith, a.

receiver, a return line conducting condensate from said device to saidreceiver, a valve controlling flow through said return line, athermostat controlling said valve, means to direct the fluid released bythe valve into heat-exchange relation with said thermostat to transferheat thereto from the released fluid thereby to cause closing action bythe valve, means to recycle the condensate from said receiver intoheat-exchange relation with said thermostat thereby to cool thethermostat when said fluid is not being released by the valve and tomodify the heating effect of the released fluid on the thermostat whenthe valve is open, and automatic means to continually vary the rate offlow of the recycled condensate.

7. In a steam system, at least one steam-using device, r. steam supplyconnected with said device, a return line in open communication withsaid supply through said device, a valve to release fluid from saidreturn line to promote flow in said device, 'boiler feed means to conveycondensate under pressure direct from said return line, a thermostatoperatively connected with said valve for closing action of the valve inresponse to temperature above its setting and opening action of thevalve in response to temperature below its setting, said thermostatbeing positioned to be heated by the discharge from said valve, means tocool said thermostat with a stream of new water flowing in response tothe demand of the system for make-up water, means to cool saidthermostat additionally with a stream of cooling fluid independent ofthe demand of the system for make-up water, and automatic means to breakup at least one of said streams of cooling uid into short flow periodsto create pulsations in the steam system.

8. In a steam system of the character described having a steam source,at least one steam-using device and a return line, thecombinationtherewith of means to promote flow velocity through the system, saidflow-promoting means includ- 15 ing: a valve to release fluid from saidreturn line into a region of substantially lower pressure, a thermostatfor causing opening operation of said valve in response to temperaturebelow a given temperature and closing operation of the valve in responseto temperature above said given temperature, said thermostat beingpositioned to be heated by the uid discharge of the valve, a means todirect make-up water into heat-exchange relation with said thermostat tocause opening action of said valve, a heat exchanger included in saidreturn line, said heat exchanger having a passage for.heating water, andmeans to direct make-up water in a pulsating manner into heat-exchangerelation with said bulb for cooling action on the bulb and subsequentlyto direct the make-up water through said passage for How-promotingcondensation in said return line.

9. In a steam system of the character described having a steam source,at least one steam-using device and a return line, the combinationtherewith of means to promote flow velocity through the system, saidflow-promoting means including: a heat exchanger included in said returnline, said heat exchanger having a passage for heating water, a receivertank maintained above atmospheric pressure but substantially below thepressure in said return line, a valve to release fluid from said returnline into said receiver, a thermostat for causing opening operation ofsaid valve in response to temperature below a' given temperature andclosing operation of the valve in response to temperature above saidgiven temperature, said thermostat being positioned to be heated by thefluid discharge from said valve, a condenser in said tank, means tocause make-up water to flow in a pulsating manner first through saidcondenser and'then into heat-exchange relation with said thermostat, andmeans to cause the make-up Water to flow subsequently through saidpassage for now-promoting condensing action in said return line. y

10. In a steam system, at least one steam-using device, a steam supplyconnected with said device,

a return line in open communication with said.

supply through said device, a receiver connected with said return line,said receiver containing a supply of make-up water for the system, avalve torelease fluid from said return line into said receiver topromote flow in the return line, a thermostat operatively connected withsaid valve for closing action of thevalve in response to temperatureabove its setting and opening action of the valve in response totemperature below its setting, said thermostat being positioned to beheated by the discharge from said valve, means to supply make-up waterto said receiver in a stream to cool said thermostat thereby to causesaid valve to open, a valve controlling said stream, and means responseto the liquid level in said receiver to repeatedly open and close saidlast mentioned valve during each time period in which the liquid isbelow a predetermined level.

11. In a steam system of the character described having a steam source,at least one steamusing device and a return line, the combinationtherewith of means to promote ilow velocity through the system, saidnow-promoting means including: a valve to release fluid from said returnline to promote flow in said device, boiler feed means to conveycondensate u nder pressure direct from said return line thereby tofurther promote ow in said device, a thermostat operatively connectedwith said valve for closing action of the valve in response totemperature above its setting and opening action of the valve inresponse to temperature below its setting, said thermostat beingpositioned to be heated by the discharge from said valve, means to coolsaid thermostat with uid to favor opening of the valve for promotingflow, and automatic means to break up the flow of said cooling fluidinto periodic flow intervals.

12. In a steam system of the character described having a steam source,at least one steamusing device and a return line, the combinationtherewith of means to promote flow velocity through the system, saidflow-promoting means including: a valve to release fluid from saidreturn line into the region of substantially lower pressure forpromoting flow in the steam system, means to bring cooling fluid intoheat-exchange relation with the contents of said return line for causingcondensation of steam therein for further promotion of flow in the steamsystem, a thermostat for causing opening operation of the valve inresponse to temperature below a given temperature and closing operationof the valve in response to temperature above said given temperature,said thermostat being positioned to be heated by the fluid dischargedfrom the valve, means to cool said thermostat with water independentlyof the make-up water demand of the system to increase the opening actionof said valve, and means to break up the ow of said cooling fluid intoperiodic flow intervals.

13. In a steam system of the character described having a steam source,at least one steamusing device and a. return line, the combinationtherewith of means to promote flow velocity through the system, saidHow-promoting means including: means to bring cooling fluid intoheatexchange relation with the contents of said return line for causingcondensation of steam therein to set up a pressure dierential across thesystem for promotion of flow in the system, a condensate pump forreturning condensate vto said boiler, said condensate pump having itsintake port in a communication with said return line to removecondensate therefrom for further promotion of flow in the system, avalve to release fluid from said return line into a region ofsubstantially lower pressure than the return line to set up a stillfurther pressure differential across the system for still furtherpromotion of flow in the steam system, a thermostat controlling saidvalve, said thermostat being positioned for rise in temperature by heatsupplied by said return line. means to cool said thermostat with fluidto modify the operation of said valve, said fluid being, at least inpart, condensate from the system, and means to break up the flow of saidcooling fluid into periodic flow intervals.

14. Ina clear channel steam system of the character described, in whichsteam is continually released from 'the return line of the system tocreate flow velocity in the system, the 'combination therewith of: meansto employ the released steam for preheating make-up water, means tocause make-up water to flow into said preheating means, and means duringperiods in which the steam system demands new water to break up saidflow of make-up water into periodic increments thereby to spread themake-up water demand over the major portion of the operating time of thesystem.

15. In a clear channel steam system, a combination as set forth in claim14, which includes 17 means to vary said increments for differentmagnitudes of make-up Water demand.

16. In a clear channel steam system, a combination as set forth in claim15, in which said varying means includes a timer continually repeating agiven cycle, said timer being adjustable with respect to the quantity ofmake-up Water flowing in each cycle.

17. In a method of operating a clear channel steam system of thecharacter described, in which steam is continually releasedlfrom thereturn end of the system to create flow velocity in the system and isused to preheat make-up water for the system, the improvement thatcomprises break-- ing up the Supply of make-up Water into periodicincrements when the system demands make-up Water, thereby spreading themake-up Water de- 18 mand over the major portion of the operating timeof the system, and releasing the steam in a corresponding series ofincrements to preheat the water increments.

ORVILLE A. HUNT. LOUIN TILLER.

REFERENCES CITED The following references arevof record in the 10 fileof this patent:

UNITED STATES PATENTS

